Development By The Numbers

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Elizabeth Miles
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1 Development By The Numbers

6 We Are Going To Measure Complexity

7 Why Should We Care About Complexity?

8 "The Central Enemy Of Reliability is Complexity" - Geer et al.

9 Complexity And Quality Are Strongly Related

11 Basic Metrics

12 Cyclomatic Complexity

13 Cyclomatic Complexity Number Of "Decision Points" In A Routine

14 function foo($a, $b) { $c = 0; if ($a) { $c = $a; elseif ($b) { $c = $b; if ($a && $b) { $c = $a + $b; return $c;

15 function foo($a, $b) { $c = 0; if ($a) { $c = $a; elseif ($b) { $c = $b; if ($a && $b) { $c = $a + $b; return $c;

16 function foo($a, $b) { $c = 0; if ($a) { $c = $a; elseif ($b) { $c = $b; if ($a && $b) { $c = $a + $b; return $c; 4

17 Simple Right?

19 Cyclomatic Complexity (Single Method) 1-4: Low Complexity 5-7: Moderate Complexity 8-10: High Complexity 11+: Very High Complexity

20 Cyclomatic Complexity (Average Per Method) 1-2: 2-4: 4-6: 6+: Low Complexity Moderate Complexity High Complexity Very High Complexity

21 Compare: Average CC per Method Wordpress: 6.28 Drupal 7: 3.02 Drupal 8: 2.10 Symfony 2: 1.81 Zend Framework 2: 2.62 Laravel: 1.79

22 Cyclomatic Complexity (Average Per Line Of Code) : : :.15+: Low Complexity Moderate Complexity High Complexity Very High Complexity

23 Compare: Average CC per LOC Wordpress: 0.20 Drupal 7: 0.04 Drupal 8: 0.07 Symfony 2: 0.06 Zend Framework 2: 0.10 Laravel: 0.07

25 N-Path Complexity

26 N-Path Complexity Number Of "Unique Paths" In A Routine

27 function foo($a, $b) { $c = 0; if ($a) { $c = $a; elseif ($b) { $c = $b; if ($a && $b) { $c = $a + $b; return $c;

28 function foo($a, $b) { $c = 0; if ($a) { $c = $a; elseif ($b) { $c = $b; if ($a && $b) { $c = $a + $b; return $c;

29 function foo($a, $b) { $c = 0; if ($a) { $c = $a; elseif ($b) { $c = $b; if ($a && $b) { $c = $a + $b; return $c;

30 function foo($a, $b) { $c = 0; if ($a) { $c = $a; elseif ($b) { $c = $b; if ($a && $b) { $c = $a + $b; return $c;

31 function foo($a, $b) { $c = 0; if ($a) { $c = $a; elseif ($b) { $c = $b; if ($a && $b) { $c = $a + $b; return $c;

32 function foo($a, $b) { $c = 0; if ($a) { $c = $a; elseif ($b) { $c = $b; if ($a && $b) { $c = $a + $b; return $c; 4

33 They Are The Same?

34 Not Generally!

35 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: NPath:

36 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: NPath:

37 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath:

38 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath:

39 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath:

40 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath:

41 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath:

42 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath:

43 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath:

44 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath:

45 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath:

46 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath: 8

47 function foo2($a, $b, $c) { $d = 0; if ($a) { $d += $a; if ($b) { $d += $b; if ($c) { $d += $c; return $d; CC: 4 NPath: 8 2^(CC-1)

48 N-Path Complexity <16: Low Complexity : Moderate Complexity : High Complexity 1025+: Very High Complexity

50 N-Path Complexity Minimum Number Of Tests Required To Completely Test A Routine

53 N-Path Complexity entity_load() CC: N-Path:

54 N-Path Complexity entity_load() CC: 2 N-Path:

55 Cyclomatic Complexity 1-4: Low Complexity 5-7: Moderate Complexity 8-10: High Complexity 11+: Very High Complexity

56 N-Path Complexity entity_load() CC: 2 N-Path: 2

58 N-Path Complexity drupal_http_request() CC: N-Path:

63 N-Path Complexity drupal_http_request() CC: 41 N-Path:

64 Cyclomatic Complexity 1-4: Low Complexity 5-7: Moderate Complexity 8-10: High Complexity 11+: Very High Complexity

65 N-Path Complexity drupal_http_request() CC: 41 N-Path: 25,303,344,960

67 To Completely Test drupal_http_request() At 1 Line Of Code Per Test Would Require 2 Terabytes Worth Of Tests

68 To Completely Test drupal_http_request() At 1 Line Of Code Per Test Would Require 412 DVD's Worth Of Tests

69 To Completely Test drupal_http_request() At 1 Line Of Code Per Test Would Require 670k Drupals Worth Of Tests

70 And That's Not The Worst One!

72 N-Path Complexity _date_repeat_rrule_process() CC: N-Path:

73 N-Path Complexity _date_repeat_rrule_process() CC: 81 N-Path:

74 N-Path Complexity _date_repeat_rrule_process() CC: 81 N-Path: 19,781,719,256

75 N-Path Complexity _date_repeat_rrule_process() CC: 81 N-Path: 19,781,719,256,250,000,000,000

76 N-Path Complexity _date_repeat_rrule_process() CC: 81 N-Path: 19,781,719,256,250,000,000,000,000,000,000

77 To Completely Test _date_repeat_rrule_process() At 1 Line Of Code Per Test Would Require 336T 2009's Worth Of Tests

78 To Completely Test _date_repeat_rrule_process() At 1 Line Of Code Per Test Would Require 1 Greenland Ice Cap of microsd cards Worth Of Tests

80 CRAP

82 CRAP (Change Risk Analysis Predictions)

83 CC = Cyclomatic Complexity (method) COV = Test Coverage (percent) CRAP = CC + (CC^2 * (1 - COV)^3)

85 CRAP Relates Complexity And Test Coverage

86 CRAP Increasing Test Coverage Lowers CRAP Decreasing Complexity Lowers CRAP

87 CRAP A Low Complexity Method With No Tests Is Good

88 CRAP A Low Complexity Method With Good Tests Is Great

89 CRAP A Moderate Complexity Method With Good Tests Is OK

90 CRAP A Moderate Complexity Method With No Tests Is CRAP

91 CRAP < 5: 5-15: 15-30: 30+: GREAT Code Acceptable Code Eih... Code CRAPpy Code

93 How Do We Apply These Metrics?

97 Sebastian Bergmann PHPUnit DbUnit PHPLOC PHPCPD PHPCOV hphpa

98 PHPLOC

99 PHPLOC By Sebastian Bergmann

100 PHPLOC By Sebastian Bergmann Command Line Tool

101 PHPLOC By Sebastian Bergmann Command Line Tool Summarizes An Entire Codebase

102 $ phploc path/to/drupal7/ Directories: 73 Files: 180 Lines of Code (LOC): Cyclomatic Complexity / Lines of Code: 0.04 Comment Lines of Code (CLOC): Non-Comment Lines of Code (NCLOC): 44026

103 Namespaces: 0 Interfaces: 1 Traits: 0 Classes: 38 Abstract: 2 (5.26%) Concrete: 36 (94.74%) Average Class Length (NCLOC): 197

104 Methods: 433 Scope: Non-Static: 378 (87.30%) Static: 55 (12.70%) Visibility: Public: 255 (58.89%) Non-Public: 178 (41.11%) Average Method Length (NCLOC): 17 Cyclomatic Complexity / Number of Methods: 3.02 Anonymous Functions: 0 Functions: 521 Constants: 22 Global constants: 15 Class constants: 7

105 PDepend

106 PDepend By Manuel Pichler (Also German)

107 PDepend By Manuel Pichler (Also German) Like PHPLOC, But Granular

108 PDepend By Manuel Pichler (Also German) Like PHPLOC, But Granular Lower Level Analysis

109

110 Fanout: Describes Outward Dependencies - Describes Dependence on Other Classes ANDC: Average Num of Derived Classes - Describes How Much Inheritance Is Used AHH: Average Hiearchy Height - Describes How Deep Of Inheritance Is Used

111 PHPMD (Mess Detector)

112 PHPMD By Manuel Pichler (German)

113 PHPMD By Manuel Pichler (German) Finds "Messy" Parts Of Code

114 PHPMD By Manuel Pichler (German) Finds "Messy" Parts Of Code Finds Rule Violations

115 PHPMD Rules CodeSize - (CC, NPath, Number of Methods, Size of Methods, etc) Design - (Eval, Goto, Exit(), Inheritance Depth) Naming - (Short names, Inconsistent Names) Unused Code Controversial - (Superglobal Access, Naming Conventions)

116

117 Prevent Complex Code From Even Getting In!

118 By Themselves Useful

119 Over Time

120 Over Time Invaluable

121 Drupal 8.x Branch Non-Comment Lines Of Code

122 Drupal 8.x Branch Number Of Classes

123 Drupal 8.x Branch Cyclomatic Complexity Per Method

124 Drupal 8.x Branch Cyclomatic Complexity Per Line

125 Drupal 8.x Branch

126

127

128

129 One More Thing To Keep In Mind

130

131

132 Anthony blog.ircmaxell.com github.com/ircmaxell youtube.com/ircmaxell

Reviewing PHP Code. Sebastian Bergmann July 27th sharing experience

Reviewing PHP Code. Sebastian Bergmann July 27th sharing experience Reviewing PHP Code Sebastian Bergmann July 27th 2011 Seba stian Why so negative? 2001 Columbia Pictures Industries, Inc. All Rights Reserved. Your code has been weighed, it has been measured, and it has